Means for eliminating fluctuations in electric current



Nov. 27, 192s.

' 1,693,258 c. SPAETH MEANS FOR ELIMINATING FLUCTUATIONS IN ELECTRIC CURRENT Filed June 7, 1926 Patented Now a7, 1928.-

UNITED STATES PATENT- OFFICE.

cnannn's sran'rn, or CHICAGO, ILLnvoIs, assmnon, .BY MESNE Assrdmms, r

narrnnon manurac'runme conrm, or cummncn; massacnusarra. a

CORPORATION OF DELAWARE.

MEANS FOR ELIHINATING FLUCTUATIONS IN ELECTRIC CUBRIM.

Application filed June 7,

My invention relates to means for and methods of eliminating objectionable eifects of slight voltage or current fluctuations in an electric current.

6 My invention is basedon the use of a thermo-couple to bring about the corrective efl'ect.

"In certain cases one thermo-couple may an swer when connected in one side of the circult and in other cases it may be desired to 10 connect a thermo-couple with each 'side of the circuit.

My inventionhas many uses,but for the pur- L direct current. It is desirable to heat this filament by alternating current because of the elimination thereby of a storage battery in view of the fact that alternating current is usedto such a large extent for distributing current; i

When electron discharge apparatus of this character is energized by alternating current,

it is necessary that one or the other of the circuits associated with the 'apparatusbe in some manner associated with a point in the filament circuit which, at any instant, represents the average potential of the filament circuit. If the filament circuit consists of wire which has absolutely uniform cross section and resistence, then the absolute center point of the filament circuit would be the point of average potential. In general, it is dilficult to locate this point exactly and the location of this point when manufacturing devices of 40 this character in commercial quantities is v quite difiicult, if not impossible. At any rate, this exact location increases the costs to such an extent that it is undesirable to be limited to the discovery of this exact point in manufacturing such devices.

In accordance with my invention, I intro-' duce a thermo-couple into the filament circuit or associate it therewith in any manner which will bring about the result and I then associate the other circuit or-auxiliary circuits of the device with the junction point of the thermo-couple. 5

When two dissimilar metals are joined toglass bulb 16 surmounts the base. The tube 1928. Serial No. 114,172.

gether and the junction point is heated and a circuit is established between the terminals ofthese two elements, then a slight current will traverse this circuit. Ifnow the conditions are reversed and a current is impressed upon the terminals of the thermo-couple, if this current does not exceed the value given out by the thermo-couple when heated, then this current is all consumed at the junction point in producingheat, which heating effect is, of course, entirely aside from the ordinary (1 R heating efl'ect. If the current is reversed, the junction point is cooled. Now, if this current fluctuates between zero and the 7 maximum given out by the thermo-couple, the potential of the current is consumed in the heatin or cooling effect as the case may be. Thus, if a small alternating current or other variable "current whose greatest value would not exceed the value of the current given off by the thermo-cou le is passed through the thermo-couple, the eating effect at the junction point would, of course, vary as the current changes its amplitude, but the voltage of the junction point would remain at a constant value.

If then such a thermo-couple be introduced somewhere near the middle point of the filament circuit and the auxiliary circuit or circuits heretofore referred to connected to the junction point, this auxiliary circuit or circuits are then connected to the point of average potential of the filament circuit.

I will explain this more in detail by referring to the accompanying drawing in which- Fig. 1 shows an electronic discharge tube constructed in accordance with my invention- Fig. 2 is a diagrammatic illustration of a thermo-couple Fig. 3 is a diagram indicating the principles involved; and

Fig. 1 shows my improved electronic device as associated in a radio receiving 011'- cuit.

Referring now more particularl to Fig. 1, I show an electronic discharge tu a base 10 provided with the customary connecting prongs 11, 12, 13 and 14. stud 15 is also shown for cooperation with the bayonet catch in the socket. An evacuated 10 itself consists of a pair of plate elements 17,

having 1 are respectively connected to the free ends of the thermo-couple consisting of the steel element 28 and the molybdenum element 29. The free extremity of the free element 29 is connected to the free extremity of the filament 24 and the free extremity of the molyb: denum element'29 is connected to the free extremity of the filament element 25. The other extremities of the elements 28 and 29 arev soldered or brazed or otherwise suitably fastened together to form a junction p int 80 from which junction point a conductor 31 leads outwardly out of the evacuated bulb 16. The thermo-electric couple consisting of the elements 28 and 29 is, of course, preferably associated in the filament circuit so that there is an equal amount of filament in so far as practical constructions can bring it about upon the opposite sides of the thermo-couple. As before stated, this is not always possible of obtainment when commercially manufac- /turing these devices. If the elements 28, 24

and 26 have exactly the same resistence as the elements 29, 25 and 27', then the junction point 30 would, of course, be at the point of average filament circuit potential. As this, however, is not readily obtainable, the thermo-couple has been introduced so that even though the point 30 is not at the exact point t of average potential (eliminating for the moment the effect of the t-hermo-couple itself), that this point 30 nevertheless will be the point of average potential when taken in connection with the efiects of the thermocouple itself.

To explain this a little'more in detail, I have shown in Fig. 2 a thermo-couple consisting of the elements 28 and 29 and having the junction point 30. In Fig. 31 show a vector diagram in which the line ab represents the base line.- If we consider the line ed as representing one-half of the maximum potential value of the impressed alternating current which we will assume is impressed upon the terminals of the filament circuit,

then :the line 6 plus the line ad will repre sent the total maximum pressure. If the line ac represents the length of the filament and we take a point midway thereof, such as the point g, and draw a line between the points; at and f, it will be seen that the point 9 is at a point of average potential, that is, throughout the entire cycle. We may assume, for

the purposes of discussion, that the point 9 is grounded as at in Thus, if the total impressed pressure 1s 6 volts, the average potential when the pressure is maximum is 3 volts and the points will always be at this point of average potential throughout the entire alternating cycle.

In a similar way the line'z'lc represents the potential when the current is flowing in the opposite direction.

Now, in practice, the point to which connection is made is generally a little bit to the right or to the left of the point g and for the purpose of illustration, we have chosen the point Z as representing the junction point 30. It then we draw the ordinates Zm and Zn to the lines 270 and (if, respectively, and

project these points over by the lines '0 and p and then draw between these lines the sinuous curve q, we will find that the variation from the point of average potential at the point Z. is represented by the sine curve 9.

In theillustration the amplitude of this curve has, of course, been very much exaggerated, as in practice the variation from the polnt of 1% oi the total impressed pressure.' However, the line 9 represents the amount of voltage change from the amount of average potential as represented by the point g.

Now if the maximum value asrepresented by the curve 9 is within the maximum current emission value of the thermo-couple, then the variations due to this curve are consumed in their heating and cooling effect of the junction point so that the junction point 30, instead of being subject tothe variations, remains at a constant potential. In other words, thethermo-couple itself within the limits of its own capabilities either absorbs or eliminates or corrects the error due to the selection of the point 30 which occurs the variations in magnetic or electrostatic effect due to the alternating currentin the filaaverage potential would probably be less than ment circuit are neutralized in these other should the device be used for radio'or similar purposes. The filament itself is, of course, selected in such away that the lag in its heating and coolingis sufiicient to prevent any objectionable influences due to a change in its thermal condition by reasons oi. the variations. inthe alternating impressed current.

In Fig, 4 I a simple detector circuit in which there is the inputtransformer having the primary 32 and secondary 33, there being also shown show my device as applied to I v a tuning condenser 34 and'a grid leak 35 My improved electron discharge deviceis also shown, as will be readily apparent, the same reference numerals being used as are used in Fig. 1. The filamentcircuit is shown as being'energized from a source of alternating current 36 through the agency of the step- .down'transformer 37. A B battery is shown at 38 and the output terminals are shown at 39, the electronic device in this instance acting as fa rectifier. I prefer to 'use a 9 bolt B battery in this instance and then associate with the circuit a- C battery 40 which assists to shift the working position of the tube to its more efiicient point on its curve. The C battery is preferably about 90 volts and I rovide a shunt resistance 41 about this C battery which may be all the way from 400 to 2,000 ohmsand which is adjustable and which helps to adjust the grid tage impressed by the C battery.

It will be seen that the input circuit of the tube includes the. elements 40 and 41 and this input circuit of the tube which includes the grid is directly connected-byjmeans of the conductor 31 with the junction point of the thermo-couple which is the point of average filament circuit potential. As the grid circuit is thus connected with a point of average filament circuit potential, the objectionable efiects of the alternating heating current are avoided and no "hum is heard due to such current. This follows, it is thought, from the descriptive matter which, has gone before From this, descrlption of the circuit/arrangement of Fig. 4, it will be readily a parent to those skilled in the art that t o .device is applicable for use [with an number of electron discharge devices. ft may be used in radio receiving sets of any character re ardless of the number'of such devices. have in this description, limited 4 v myself to describing in detail one form which rny invention-may take, but I'have also stated in the lntroductory portion of the specification that the principle of the invention is applicable for a great variety of uses and edto maintain at'an average potential a given point. of said filament circuit which except for said thermo-electric couple would not represent the point of average potential of said filament ClICllltn r 2. An electron discharge device having a casing, a filament circuit therein, a thermocouple associated with said filament circuit,

and a connectionbetween the junction point of said thermo-cou le and the circuit including one of the ot er elements of said device. g

3. An electron discharge device having a casing, a filament circuit therein, a thermocouple interposed substantially midway of said filament circuit and a. connectionbetween the junction point of said thermo-couple and the circuit including one of the other elements of said device.

my namethis 19th day of May A. D., 1926.

, CHARLES SPAETH.

In witness whereof, I hereunto subscribe 

